System and Method for Multiple Access Based on Power Profiles

This application is a continuation of International Application No. PCT/CN2022/129981, filed on Nov. 4, 2022, titled “SYSTEM AND METHOD FOR MULTIPLE ACCESS BASED ON POWER PROFILES,” which is hereby incorporated by reference in its entirety.

The application relates to wireless communications generally, and more specifically to systems and methods of multiple access in wireless communications systems.

In machine type communication (MTC), it is very common that a cluster or a group of user equipment (UE) to communicate with the one or more base station(s) (BSs) on the network side. The UE can be a sensor, machine type device, internet of things (IoT) device or other. Such a scenario may be very common in a factory industrial environment such as an assembly line. The link from the UE side to network/BS(s) is commonly referred to as the uplink, and the link from the BS/network to the UE side is commonly referred to as the downlink; a link between one UE and another UE is commonly referred to as the sidelink. The signal from a transmitter to a receiver is propagated over a propagation channel, commonly known as channel. The channel can be characterized by its statistical nature or random variable(s). For example, a channel from a transmitter to a receiver can be characterized by many random parameters such as amplitude, phase, angle of arrival (AoA), angle of departure (AoD), path loss, spatial parameters such as AoA, dominant AoA, average AoA, power angular spectrum (PAS) of AoA, average AoD, PAS of AoD), Doppler spread/shift, delay, delay spread. In some scenarios, one or more of channels or channel parameters can be correlated with another channel or channel parameters. Such channels can be uplink or downlink or sidelink channels. The channel correlation means that one or several parameters of the propagation channels are correlated or interdependent. Such parameters show a statistical relationship between them or some other form of associations. Correlation normally can refer to the degree to which one parameter provides statistical information about the other. In a specific example, an uplink channel from a first UE to a BS can be correlated with another uplink channel from a second UE to the BS. In another specific example, an uplink channel from the first antenna of a first UE to a BS can be correlated to an uplink channel from the second antenna of the first UE to the BS.

The most familiar measure of dependence between two quantities is the Pearson product-moment correlation coefficient (PPMCC), or commonly called “the correlation coefficient.” The correlation coefficient is obtained by taking the ratio of the covariance of the two quantities, normalized to the square root of their variances. If the variables are independent, the correlation coefficient is 0. A non-zero correlation coefficient indicates a form of dependence between the quantities. In a specific scenario, full correlation means the absolute value of the correlation coefficient is 1, i.e., one quantity fully characterizes the other such that there is full dependence.

Correlation in physical channels can occur due to various reasons. For example, when two antennas are closely placed in an antenna array, their channels can be correlated. When a cluster/group of UEs are geographically close to one another, their propagation channels can be highly correlated or their path loss/propagation loss can be very similar. When channels are highly correlated, it means their propagation characteristics are very similar as well.

When two transmissions are propagated to a receiver over dissimilar channels (e.g. independent channels), although they interfere to one another, these transmissions can be separated at the receiver using the dissimilar channels. When channels are highly correlated, the channels are similar and therefore, it is difficult for the receiver to separate those signals.

In accordance with an embodiment of the disclosure, the power of each modulated constellation symbol of a sequence of modulated symbols to be transmitted is set according to a respective amplitude scaling factor of a known power profile. The power profile is known in the sense that the entire set of amplitude scaling factors of the power profile is known to both transmitter and receiver before it is applied. The set of amplitude scaling factors applied to the sequence of modulated symbols of a given transmission is collectively referred to herein as the power profile. More generally, each of a plurality of parts of a signal has a respective amplitude scaling factor from the known power profile applied. Examples of such a power profile include a power control pattern or a power allocation pattern, both described in detail below. In this embodiment, the power profile is also referred to herein as an intra-slot power profile. The power profile may be provided to the transmitter side through signaling such as radio resource control (RRC), medium access control-control entity (MAC-CE), downlink control information (DCI) signaling or a combination thereof. In some scenarios such as a grant-based or scheduled transmission scenario, the power profile is assigned/configured to the transmitter from the network side while in some other scenarios such as grant-free or configured-grant transmission scenario, the transmitter may select/choose/determine one power profile out of a table or pool of power profiles. Configurations such as time granularity, frequency granularity, amplitude scaling factors and other transmission parameters and configurations are signaled from the network side in advance through signaling such as RRC, MAC-CE, DCI signaling or a combination thereof. After applying the power profile to the sequence of modulated symbols, a waveform operation such as DFT spreading (for DFT spread OFDM) may be performed. In some other embodiments, DFT spreading may be performed before applying the power profile/amplitude scaling factors.

According to one aspect of the present disclosure, there is provided a method comprising: communicating a signal over a wireless communications channel, the signal being based on a plurality of parts to each of which a respective one of a plurality of amplitude scaling factors has been applied, the plurality of amplitude scaling factors collectively forming a known power control pattern or a known power allocation pattern.

In some embodiments, the amplitude scaling factors do not depend on data carried by the signal.

In some embodiments, communicating a signal comprises transmitting the signal.

In some embodiments, communicating a signal comprises receiving the signal.

In some embodiments, the plurality of parts comprise: a plurality of modulated symbols; or a plurality of groups of resource elements; or a plurality of groups of modulated symbols; or a plurality of groups of subcarriers; or a plurality of resource blocks; or a plurality of modulated symbols for transmitting a forward error correction (FEC) codeword; or a plurality of OFDM symbols; or a plurality of slots in the time domain; a plurality of retransmissions; or a plurality of repetitions.

In some embodiments, the method further comprises performing power control pattern or power allocation pattern hopping in time or in frequency or in time and frequency.

In some embodiments, the method further comprises obtaining the power control pattern or power allocation pattern from a pool of power control patterns or power allocation patterns.

In some embodiments, obtaining the power control pattern or power allocation pattern from a pool of power control patterns or power allocation patterns comprises: choosing the power control pattern or power allocation pattern or an index of the power control pattern or power allocation pattern at random; obtaining an index of the power control pattern or power allocation pattern using a formula; choosing the power control pattern or power allocation pattern to achieve an acceptable PAPR; measuring a channel to obtain channel measurements and choosing the power control pattern or power allocation pattern based on channel measurements; receiving feedback reflecting channel measurements and choosing the power control pattern or power allocation pattern based on the feedback.

In some embodiments, the method further comprises communicating signaling defining one or more of: the power control pattern or power allocation pattern; or an index of the power control pattern or power allocation pattern within a pool of power control patterns or power allocation patterns; or configuration of bit-level processing to be performed as part of generating the signal; or configuration of symbol-level processing to be performed as part of generating the signal; or configuration of bits-to-symbol mapping to be performed as part of generating the signal.

In some embodiments, the signal is a non-orthogonal multiple access (NoMA) signal, and wherein the signal has a multiple access (MA) signature based at least in part on the power control pattern or power allocation pattern.

In some embodiments, the method further comprises obtaining channel measurements and transmitting information concerning the channel measurements to a transmitter for use in determining the power control pattern or power allocation pattern.

In some embodiments, the method further comprises receiving one or more power control commands that cause the signal to be transmitted with the power control pattern or power allocation pattern.

In some embodiments, the method further comprises transmitting one or more power control commands that cause the signal to be transmitted with the power control pattern or power allocation pattern.

In some embodiments, the method further comprises communicating signaling enabling or disabling the application of the plurality of amplitude scaling factors.

According to another aspect of the present disclosure, there is provided a network device comprising: a processor and a memory, the network device configured to perform a method for receiving downlink control information (DCI), the method comprising: communicating a signal over a wireless communications channel, the signal being based on a plurality of parts to each of which a respective one of a plurality of amplitude scaling factors has been applied, the plurality of amplitude scaling factors collectively forming a known power control pattern or a known power allocation pattern.

In some embodiments, the amplitude scaling factors do not depend on data carried by the signal.

In some embodiments, wherein communicating a signal comprises transmitting the signal.

In some embodiments, communicating a signal comprises receiving the signal.

In some embodiments, the plurality of parts comprises: a plurality of modulated symbols; or a plurality of groups of resource elements; or a plurality of groups of modulated symbols; or a plurality of groups of subcarriers; or a plurality of resource blocks; or a plurality of modulated symbols for transmitting a forward error correction (FEC) codeword; or a plurality of OFDM symbols; or a plurality of slots in the time domain; or a plurality of retransmissions; or a plurality of repetitions.

In some embodiments, the method the network device is configured to perform further comprises performing power control pattern or power allocation pattern hopping in time or in frequency or in time and frequency.

In some embodiments, the method the network device is configured to perform further comprises: obtaining the power control pattern or power allocation pattern from a pool of power control patterns or power allocation patterns.

In some embodiments, obtaining the power control pattern or power allocation pattern from a pool of power control patterns or power allocation patterns comprises: choosing the power control pattern or power allocation pattern or an index of the power control pattern or power allocation pattern at random; obtaining an index of the power control pattern or power allocation pattern using a formula; choosing the power control pattern or power allocation pattern to achieve an acceptable PAPR; measuring a channel to obtain channel measurements and choosing the power control pattern or power allocation pattern based on channel measurements; receiving feedback reflecting channel measurements and choosing the power control pattern or power allocation pattern based on the feedback.

In some embodiments, the method the network device is configured to perform comprises communicating signaling defining one or more of: the power control pattern or power allocation pattern; or an index of the power control pattern or power allocation pattern within a pool of power control patterns or power allocation patterns; or configuration of bit-level processing to be performed as part of generating the signal; or configuration of symbol-level processing to be performed as part of generating the signal; or configuration of bits-to-symbol mapping to be performed as part of generating the signal.

In some embodiments, the signal is a non-orthogonal multiple access (NoMA) signal, and wherein the signal has a multiple access (MA) signature based at least in part on the power control pattern or power allocation pattern.

In some embodiments, the method the network device is configured to perform further comprises: obtaining channel measurements and transmitting information concerning the channel measurements to a transmitter for use in determining the power control pattern or power allocation pattern.

In some embodiments, the method the network device is configured to perform further comprises: receiving one or more power control commands that cause the signal to be transmitted with the power control pattern or power allocation pattern.

In some embodiments, the method the network device is configured to perform further comprises: transmitting one or more power control commands that cause the signal to be transmitted with the power control pattern or power allocation pattern.

In some embodiments, the method the network device is configured to perform further comprises: communicating signaling enabling or disabling the application of the plurality of amplitude scaling factors.

According to another aspect of the present disclosure, there is provided an apparatus comprising a processor and a memory, the apparatus configured to perform a method for receiving downlink control information (DCI), the method comprising: communicating a signal over a wireless communications channel, the signal being based on a plurality of parts to each of which a respective one of a plurality of amplitude scaling factors has been applied, the plurality of amplitude scaling factors collectively forming a known power control pattern or a known power allocation pattern.

In some embodiments, the amplitude scaling factors do not depend on data carried by the signal.

In some embodiments, communicating a signal comprises transmitting the signal.

In some embodiments, communicating a signal comprises receiving the signal.

In some embodiments, the plurality of parts comprises: a plurality of modulated symbols; or a plurality of groups of resource elements; or a plurality of groups of modulated symbols; or a plurality of groups of subcarriers; or a plurality of resource blocks; or a plurality of modulated symbols for transmitting a forward error correction (FEC) codeword; or a plurality of OFDM symbols; or a plurality of slots in the time domain; or a plurality of retransmissions; or a plurality of repetitions.

In some embodiments, the method the apparatus is configured to perform further comprises performing power control pattern or power allocation pattern hopping in time or in frequency or in time and frequency.

In some embodiments, the method the apparatus is configured to perform further comprises: obtaining the power control pattern or power allocation pattern from a pool of power control patterns or power allocation patterns.

In some embodiments, obtaining the power control pattern or power allocation pattern from a pool of power control patterns or power allocation patterns comprises: choosing the power control pattern or power allocation pattern or an index of the power control pattern or power allocation pattern at random; obtaining an index of the power control pattern or power allocation pattern using a formula; choosing the power control pattern or power allocation pattern to achieve an acceptable PAPR; measuring a channel to obtain channel measurements and choosing the power control pattern or power allocation pattern based on channel measurements; receiving feedback reflecting channel measurements and choosing the power control pattern or power allocation pattern based on the feedback.

In some embodiments, the method the apparatus is configured to perform comprises communicating signaling defining one or more of: the power control pattern or power allocation pattern; or an index of the power control pattern or power allocation pattern within a pool of power control patterns or power allocation patterns; or configuration of bit-level processing to be performed as part of generating the signal; or configuration of symbol-level processing to be performed as part of generating the signal; or configuration of bits-to-symbol mapping to be performed as part of generating the signal.

In some embodiments, the signal is a non-orthogonal multiple access (NoMA) signal, and wherein the signal has a multiple access (MA) signature based at least in part on the power control pattern or power allocation pattern.

In some embodiments, the method the apparatus is configured to perform further comprises: obtaining channel measurements and transmitting information concerning the channel measurements to a transmitter for use in determining the power control pattern or power allocation pattern.

In some embodiments, the method the apparatus is configured to perform further comprises: receiving one or more power control commands that cause the signal to be transmitted with the power control pattern or power allocation pattern.

In some embodiments, the method the apparatus is configured to perform further comprises: transmitting one or more power control commands that cause the signal to be transmitted with the power control pattern or power allocation pattern.

In some embodiments, the method the apparatus is configured to perform further comprises: communicating signaling enabling or disabling the application of the plurality of amplitude scaling factors.

Different techniques may be used to separate the transmissions that are sent over correlated channels. One such method is to use orthogonal resources for each transmission. When two transmissions use orthogonal physical resources, commonly known as orthogonal multiple access (OMA), every transmission requires distinct physical resources which leads to poor physical resource usage and hence less throughput in the system. In another approach, non-orthogonal multiple access (NoMA) can be used, where signatures that are orthogonal (orthogonal signatures have zero correlation between signatures) or near orthogonal (near orthogonal means that the correlation between the signatures is low) can be used to separate the transmissions. However, only a certain number of near-orthogonal or orthogonal signatures can be defined for a given physical resource with a given level of signature correlation. As a result, OMA or orthogonal/near-orthogonal signature based approaches can lead to poor system efficiency as well.